Neuroscience 2002 Abstract
| Presentation Number: | 559.2 |
|---|---|
| Abstract Title: | PATTERN SPECIFIC ATTENTIONAL MODULATION OF V4 SPATIOTEMPORAL RECEPTIVE FIELDS DURING FREE-VIEWING VISUAL SEARCH. |
| Authors: |
David, S. V.*1
; Mazer, J. A.2
; Gallant, J. L.2
1Bioengineering, University of California, Berkeley, Berkeley, CA 2Psychology, University of California, Berkeley, Berkeley, CA |
| Primary Theme and Topics |
Sensory Systems - Vision -- Extrastriate visual cortex: Attention and cognition |
| Secondary Theme and Topics | Sensory Systems<br />- Vision<br />-- Extrastriate visual cortex: Orientation, form and color |
| Session: |
559. Visual cortex: attentional effects Poster |
| Presentation Time: | Tuesday, November 5, 2002 2:00 PM-3:00 PM |
| Location: | Hall A2-B3 F-59 |
| Keywords: | NATURAL SCENES, NEURAL CODING, NEUROETHOLOGY, EYE MOVEMENT |
Single neurons in macaque area V4 were recorded during an attentionally demanding free-viewing visual search task. Eye movements and neuronal activity were recorded while the subject inspected a sample target (a 3-6 deg B&W natural scene photograph) for 2-3s. The subject had to report the appearance of the sample within an array of distractor photographs.
Under these conditions some V4 neurons show non-spatial, pattern-specific modulations of firing rate dependent on search target (see Mazer et al; SFN Abs. 2001). To further characterize these changes, we used reverse correlation to compute spatiotemporal receptive fields (STRFs) contingent on the search target. Each STRF is a model of a cell's selectivity for stimulus orientation, spatial frequency and spatial phase.
The complex statistics of visual stimuluation during free-viewing make it difficult to determine whether STRF changes reflect attentional modulation or are merely due to the spectral properties of the stimuli falling in the receptive field during search. To solve this problem we projected STRFs obtained in each attentional state into a subspace defined by the five largest principal components of the stimuli. This approach allowed us to accurately identify selectivity changes due solely to attentional state and not to stimulus bias.
For more than 80% of the V4 neurons studied, this analysis revealed significant STRFs changes in at least one of the attentional states relative to baseline (n=36; corrected p<0.05). These results indicate that V4 neurons dynamically change their orientation and spatial frequency tuning during complex search, depending on high level task demands.
Under these conditions some V4 neurons show non-spatial, pattern-specific modulations of firing rate dependent on search target (see Mazer et al; SFN Abs. 2001). To further characterize these changes, we used reverse correlation to compute spatiotemporal receptive fields (STRFs) contingent on the search target. Each STRF is a model of a cell's selectivity for stimulus orientation, spatial frequency and spatial phase.
The complex statistics of visual stimuluation during free-viewing make it difficult to determine whether STRF changes reflect attentional modulation or are merely due to the spectral properties of the stimuli falling in the receptive field during search. To solve this problem we projected STRFs obtained in each attentional state into a subspace defined by the five largest principal components of the stimuli. This approach allowed us to accurately identify selectivity changes due solely to attentional state and not to stimulus bias.
For more than 80% of the V4 neurons studied, this analysis revealed significant STRFs changes in at least one of the attentional states relative to baseline (n=36; corrected p<0.05). These results indicate that V4 neurons dynamically change their orientation and spatial frequency tuning during complex search, depending on high level task demands.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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